v6-7 v8-10 trouble lights on new model t are on!!!

[Anonymous]

i dont know what this means.
i flashed a tube last week and just got it back with new ones that are supposedly better, but i was working out some parts yesterday and played for about 2 hours till i noticed the lights in the back were on. i have no idea as to how long they had been on but i havent really touched it scince.

if anyone has an information on this it would be much obliged.

thanks,
            gavin

[Anonymous]

anything??

[Geoff]

Forgive my ignorance:

What does "flashed a tube" mean?  Do you mean it went bad in some way?  What do the trouble indicator lights indicate?  Are these power tubes or preamp tubes?  Thanks for elaborating.

[Anonymous]

it flashed bright blue and orange and died..it was scary.

they are power tubes. and im not even sure what the lights mean

they are "trouble indicators"

for the power tubes..
the guy who jsut changed the tubes wasnt a sunn specialist and said that he fuckign hated the things.

sorry for being such a vauge moron.

[Geoff]

Just a guess, if the amp sounds fine still and the tubes look good -- not "cherried", the trouble lights could have been on the whole time since you got it back.  I suspect that the trouble indicators could have something to do with varying from the factory bias spec.  The tubes might be biased hotter or colder than some magic Fender-specified range.  This is done to fine tune for tone or power output or tube life, etc. (not at the same time, of course!)  I'd call the tech who put in the new tubes and tell him your problem.

I couldn't get a hold of the factory manual but here's a dibby-dab from the Fender site about your model:

The TROUBLE LED’s and BIAS POTS let the user diagnose failed output tubes, install new tubes, and set the optimum bias without the aid of a technician. This saves the customer time and money.

Good luck!

[Anonymous]

geoff is a good man

i will take it to the guy and he will yell at me

(im a shrimp)
i dotn knwo anyting about bias's

i dotn ewven know what it is

can some one refer me to a lame perosns reference to basic tube amp jargon ?

or how ever that sentence was supossed to sound.

[Geoff]

Gavin,

Well, the bias thing was just a guess but it may be the "problem".  If the tubes are operating correctly, probably not a real problem at all.  All you need to ask the guy is "why do the trouble lights glow when I operate the amp?" and ask him to explain it to you -- come back here and post his reply.

As far as explaining of tube amp workings, some helpful links I've found are:

The Lord Valve Bias FAQ: http://www.duncanamps.com/technical/lvbias.html

Aiken Amplification: http://www.aikenamps.com/

The latter has a lot of good info and links and is pretty easy to understand.  The LV FAQ above that gets right into how to bias but is pretty thorough.  After reading this stuff, you will be ready to speak more condifently with your tech.  Don't worry about him not liking Sunn stuff.  The local amp guy here hates Sunn stuff (of the vintage variety, mostly) but he wants to make $$...so I'm sure he puts aside his prejudices for that!  Slammin' the Sunn gear isn't fun to listen to but all that matters is that you have playable, reliable gear.

Aside from the knowledgeable people here, read alt.guitar.amps if you have Usenet ng capabilities -- lots of folks there can help.

[Geoff]

...I meant "confidently" instead of "condifently".  Sorry -- I really do need to proofread before I post.

[Anonymous]

......

confused
those pages require basic analog circut knowledge.but thats ok


i dont have any


im contemplating going to a specialist but i already spent most of my extra money on the first tube change. and it would be nice if the guy who did it wrong would fix it for free but im sure it wont happen. and im sure he will give my puny ass a hard time.

ohh well
its all part of owning a peice of heaven

[TubeMan]

If you want to send it to me, i will see what i can do.
i dont know why anyone doesnt like sunn stuff.. i mean all you have to do is listen to a well maintained vintage Sunn and youre hooked.

in fact.. i just installed dual bias and a new set of 6550WE Sovteks in mine (A212 Combo)..talk about SWEEET

[JoeArthur]

Well, this is probably not going to help.

I don't have my schematic for the fenderized version of the model T available.  Talking 6550's here ain't going to help when the power tube is a 6L6GC.

Flashing a tube, to me doesn't make any sense.  The flash is what is provided by the "getter" in the tube, generally causing a silvery area on the inside of the glass envelope.  They flash it to make sure all of the remaining oxygen is burned out of the partial vacuum in the tube - so that it lasts longer.

What I do remember from the schematic, is that the fenderized Model T has indicator lights.  A complex circuit determines when to light the indicator lights.  It could mean a too low bias or even possibly a no bias condition.

Bias... is a voltage applied between the control grid and cathode... to determine the operating point of the tube.  If the bias voltage is too low then the tubes will draw too much current and burn out quickly.  Too high and the sound becomes really lousy as the tubes approach class C operation (used in radio transmitter power amplifiers where distortion doesn't matter).

So chances are pretty good the indicators are for a too low a bias condition.  

There should be a bias adjustment pot somewhere.  If you can find it you can probably adjust it until the lights go out.  

However, it could also mean that the tubes you replaced and paid dollars for weren't worth it... as in an internal short.  This has been known to happen.